Refractory material



ttented June 12, 1928.

l UNITED STATES muss s'wwaouu PATENT OFFICE.

JOSEPH G. DoNA Dson AND HENRY L. COLES, on iTAMITToN, QHIO, ASSIGNORS To GUARDIAN METALS COMPANY, or HAMIL oN, 0310, A coRroRATIon' on DELA- WAR-E.

No Drawing. Original applications flledNovember RErRAoToRY MATERIAL.

17, 1922, Serial No. 601,616, and January 16, 1925,

.Serial No. 2,864. Divided and this application filed July 3, 1926. Serial No. 120,518.

The subject matter of this invention was originally disclosed in the applications for Letters Patent of Joseph G. Donaldson and Henry L. Coles, S. N. 601,616, filed Nov. 17, 1922, and Serial No. 2,864, filed January 16, 1925, and entitled Refractory materials.

r This invention relates to steel and other I metals suitable for use in the safe and vault- We do not, however, limit ourselves to the use of this material as a core as the same has many commercial uses outside of its use as a core material. I

We have found that highly refractory materials can-be formed by taking a highmelting point oxide-such as the oxide of zirconiumand binding this to ether with a suitable binder suchas a high-melting point silicate. Zirconium silicate has been found togive excellent results for this ,pur-

pose. Preferably these materials should be finely comminuted and thoroughly mixed. They should then be placed in an electric furnace and heated for a sufficient length of time to permit the whole massto become thoroughly fused.

Instead of adding the zirconium silicate as such, we have obtained excellent results by adding tothe zirconium oxideapproxi-v mately 9 to 11% silicon dioxide. When these substances have been comminuted and thoroughly mixed, the silicon'dioxide and .zirconium dioxide form\ zirconium silicate which, bein in contact with an excess of zirconium ioxide, forms mixed crystals with. the same and acts as a binder for the entire mass. To either of the above substances we have found 'it' highly advantageous to add from 7 to 10 per cent of carbon in a suitable form, such as graphite. A

typical formula covering such a mixture. is

as follows:

Per cent. Grraphlteuu 7 to 9% Silicon dioxide (SiO 9 to 11 Zirconium dioxide (ZrO,) 80 /2tO82 Ag It is our present belief that the silicon dioxide should not exceed 12% of the entire formula.

Ores containing zirconia or zirconium silicate not infrequently carry impurities of iron and titanium oxide. WVe have found that these materials are detrimental to the formula and that the best results are ob- Searcn may.

tained when either of these impurities constitute s less than 1% of the formula. The addition of carbon to the formula adds very greatly to the resistance of the finished material. This is doubtless brought about by the fact that the carbon formsmetallic carbides which are present as crystals or in solid solution.

When the material herein described is used as a core, it is given a suitable size and shape and combined with a suitable metal, 7

such as steel, as by being encased wholly or partially therein. The core is preferably placed in a mould, metal (such as steel) being poured around it, as described in our former application. Thereupon the core material and encompassing) material are brought into permanent union y the alloying action which takes place at and adjacent to theareas in contact. The mass so alloyed is more highly resistant to penetration either by the drill or by the torch than any other parts of the material not subject to such alloying action. In the matter of attempt to penetrate b means of the localized application of high eat, an im ortant factor is the capacity of the materlal to conduct the heat away from the point of attack, thereby,-in efiect, diminishing the available cutting or fusing power of the torch. Refractory materials, of the type described, are excellent non-conductors of heat when cold but become conductors of heat when raised to a high temperature and thus serve to dissipate the heat.

Cores containing a large proportion Ofx zirconia have been found to shrink considerably when the same are cooled. To overcomethis objection, we frequently break up the core after the first. melting and remelt same. The core formed by this second fusion will be found to be practically free from shrinkage cracks and to be more'coherent than those cores which have been fused only once. These cores can be put in in strata which maybe continuous throughout the metal or they may be placed in blocks which are set in staggered courses orthe material may be broken into any desired size or the core' may be formed by binding together with a suitablebinder the broken pieces, all-as set forth in our previous application. In any event, the cores, made as herein described, are intensely hard and impenetrable by the drill. They are also substantially immunefrom attack by the blow torch. F iirthermo're, the. core material, being a non-conductor of electricity, it is impossible to penetrate the same by means of the local application of the electric arc. I Havingnow described our invention; what weclaimand desire to secure by Letters Patent is I a A refractorymaterial comprising more than 85% of. zirconium dioxide, less than 15% of. silicon dioxide, and less than 10% carbon, the'car'bon being dissolved in the silicate formed duringfusing of the, oxides.

This specification signed this 129 dayiof June, 1926. I y

\ JOSEPH G. DONALDSON'. HENRY L. COLES. 

